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Claude Sonnet 4.5 vs GPT OSS 120B

Compare Claude Sonnet 4.5 by Anthropic against GPT OSS 120B by OpenAI, in 25 community votes, claude sonnet 4.5 wins 70% of head-to-head duels, context windows of 200K vs 131K, tested across 38 shared challenges. Updated April 2026.

Which is better, Claude Sonnet 4.5 or GPT OSS 120B?

Claude Sonnet 4.5 is the better choice overall, winning 70% of 25 blind community votes on Rival. Claude Sonnet 4.5 costs $3/M input tokens vs $0.18/M for GPT OSS 120B. Context windows: 200K vs 131K tokens. Compare their real outputs side by side below.

Key Differences Between Claude Sonnet 4.5 and GPT OSS 120B

Claude Sonnet 4.5 is made by anthropic while GPT OSS 120B is from openai. Claude Sonnet 4.5 has a 200K token context window compared to GPT OSS 120B's 131K. On pricing, Claude Sonnet 4.5 costs $3/M input tokens vs $0.18/M for GPT OSS 120B. In community voting, In 25 community votes, Claude Sonnet 4.5 wins 70% of head-to-head duels.

In 25 community votes, Claude Sonnet 4.5 wins 70% of head-to-head duels. Claude Sonnet 4.5 leads in Reasoning, Image Generation. Based on blind community voting from the Rival open dataset of 25+ human preference judgments for this pair.

Web Design: Claude Sonnet 4.5 and GPT OSS 120B are tied
Reasoning: Claude Sonnet 4.5 wins 71% of votes
Image Generation: Claude Sonnet 4.5 wins 100% of votes
Our Verdict
Claude Sonnet 4.5
Claude Sonnet 4.5Winner
GPT OSS 120B
GPT OSS 120BRunner-up

Pick Claude Sonnet 4.5. In 25 blind votes, Claude Sonnet 4.5 wins 70% of the time. That's not luck.

Claude Sonnet 4.5 particularly excels in Image Generation, Reasoning. GPT OSS 120B is 19x cheaper per token — worth considering if cost matters.

Clear winner
Writing DNA

Style Comparison

Similarity
97%

Claude Sonnet 4.5 uses 4.9x more sentence length

Claude Sonnet 4.5
GPT OSS 120B
64%Vocabulary52%
94wSentence Length19w
0.48Hedging0.28
4.9Bold7.4
8.0Lists1.8
0.45Emoji0.15
1.91Headings0.73
0.07Transitions0.17
Based on 20 + 21 text responses
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Claude Sonnet 4.5GPT OSS 120B

279 AI models invented the same fake scientist.

We read every word. 250 models. 2.14 million words. This is what we found.

AI Hallucination Index 2026
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